no refund for factory fault

I bought a phone on the 1st of July 2018, the 24th of July I took it back to the store as the phone would spontaneously restart. I was told by the store manager that the phone will be sent for repairs and that I should collect the phone in two weeks time. it is now the 22nd of August 2018 and nothing has been done about my phone. the manager informed me that the part that the part used to "fix" the problem was rejected by the phone. the phone was then sent back again to repairs but no one can give me answers. when I asked about a refund the store told me that I cannot get a refund as the phone was not insured. I would like some light shed on the situation of my cell phone or a complete refund.